Brain's Problem-Solving Processes Found Active During Daydreams

A new study revealed that human brains are much more active when daydreaming than previously thought.

The study, published in the May 11, 2009, issue of the journal Proceedings of the [U.S.] National Academy of Sciences (PNAS) revealed that activity in many brain regions increases when the mind wanders. It also finds that brain areas associated with complex problem solving--previously thought to go inactive when daydreaming--are in fact highly active during these episodes.

"Mind-wandering is typically associated with negative things like laziness or inattentiveness,” said lead author, Prof. Kalina Christoff, department of psychology at the University of British Columbia (UBC; Vancouver, BC, Canada). "But this study shows our brains are very active when we daydream--much more active than when we focus on routine tasks.”

For the study, when study participants were placed inside a functional magnetic resonance imaging (fMRI) scanner, where they performed the simple routine task of pushing a button when numbers appear on a screen. The researchers monitored subjects' attentiveness moment-to-moment through brain scans, subjective reports from subjects and by tracking their performance on the task.

The study's findings suggest that daydreaming, which can occupy as much as one-third of waking lives, is an important cognitive state where people may unconsciously turn attention from immediate tasks to sort through important problems in their lives.

Until now, the brain's "default network," which is linked to easy, routine mental activity and includes the medial prefrontal cortex (PFC), the posterior cingulate cortex, and the temporoparietal junction, was the only part of the brain believed to be active when minds wander. However, the study finds that the brain's "executive network”--associated with high-level, complex problem solving and including the lateral PFC and the dorsal anterior cingulate cortex--also becomes activated when we daydream. "This is a surprising finding, that these two brain networks are activated in parallel,” stated Prof. Christoff. "Until now, scientists have thought they operated on an either-or basis--when one was activated, the other was thought to be dormant.” The less subjects were aware that their mind was wandering, the more both networks were activated.

The quantity and quality of brain activity suggests that people trying to solve complicated problems might be better off switching to a simpler task and letting their mind wander. "When you daydream, you may not be achieving your immediate goal, say reading a book or paying attention in class, but your mind may be taking that time to address more important questions in your life, such as advancing your career or personal relationships,” concluded Prof. Christoff.

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